1. Field of the Invention
This invention relates to an improvement of a hydraulic pressure control device for double piping used in a hydraulic system for vehicle brakes.
2. Description of the Prior Art
It is well known that, in order to prevent wheels of a vehicle from coming into a locked state, a braking force to be applied to the rear wheels must be less than a braking force to be applied to the front wheels. To meet this requirement, there has been provided a hydraulic pressure control device capable of appropriately allocating braking hydraulic pressure to the front and rear wheels, with the hydraulic pressure being approximately proportional to the braking force to be applied to these wheels. Since the brake to be applied to a vehicle is extremely important in the safety arrangement required for the vehicle in general, the hydraulic pressure control device must have high reliability. In view of this, there has been provided a braking hydraulic system of a double piping type comprising two independent hydraulic pressure channels to ensure that a certain degree of a braking force can be secured even if one of the two channels becomes defective. Further, there has been also provided a double piping hydraulic pressure control device which is capable of performing brake oil pressure control over such a hydraulic system to have both the two independent channels thereof controlled thereby in common with each other.